Method for sand consolidation



Feb. 27, 1962 w, wlNSAUER ET AL 3,022,825

METHOD FOR SAND CONSOLIDATION Filed Sept. 8, 1958 UNCONSOLIDATEDFORMATION TREATED ZONE '1 IO l6 ll V I4 x: I

1I T? z s I4 A I 8 UNCONSOLIDATED cEMENT FORMATION INVENTORS.

WELDON O. WINSAUER,

JACK H. EDWARDS,

ATTORNEY.

United States Patent 3,022,825 METHOD FOR SAND CONSOLIDATION Weldon 0.Winsauer and Jack H. Edwards, Houston,

Tex., assignors, by mesne assignments, to Jersey Production ResearchCompany, Tulsa, Okla., a corporation of Delaware Filed Sept. 8, 1958,Ser. No. 759,511 8 Claims. (Cl. 166-33) This invention is primarilydirected to a method for consolidating loose or incompetent formationspenetrated by a borehole. More particularly, this invention is directedto an improved method for injecting sand consolidation fluids intosubsurface formations in order to consolidate the sands therein.

In producing fluids from subsurface formations, sand is produced alongwith the formation fluids from loosely consolidated formations. Becauseproduction of sand with its attendant accumulation in the well bore ormovement to the surface is undesired, various sand control measures havebeen used to inhibit or prevent sand particles from moving into the wellbore. One control measure is the use of porous setting plastics whichbind the sand particles together while permitting flow of well fluidstherethrough. Particularly good consolidating plastics of this type makeuse of the resin-forming properties of the reaction between a watersoluble aldehyde and a low molecular weight hydroxy aryl compoundcatalyzed by an alkaline or acidic catalyst. When these compounds areinjected into a sand formation, a resin forms which cements theparticles of the formation together. Although any water soluble aldehydemay be used, formaldehyde, acetaldehyde, propionaldehyde, or mixturesthereof are preferred. The low molecular weight hydroxy aryl compoundmay include phenol, cresol, beta naphthol, resorcinol, or cresylic acid,or mixtures thereof. Suitable alkaline catalysts which may be usedinclude guanidine salts such as guanidine carbonate and amino-guanidinebicarbonate; alkali metal hydroxides and carbonates such as sodiumhydroxide or sodium carbonate; aliphatic amines such as ethyl amine andtriethyl amine; aromatic amines such as aniline; and aliphatic diaminessuch as ethylene diamine. Suitable acidic catalysts which may be usedinclude acidic salts such as stannous chloride or magnesium chloride;mineral acids such as hydrochloric acid or sulfuric acid; acidanhydrides such as maleic 'anhydride; aromatic acids such as picric acidor benzene sulfonic acid or sulfanilic acid; and polynuclear aromaticacids or acid salts such as alpha naphthylamine sulfonic acid or sodium-1-naphthylamine-3,6,8 trisulfonate.

In order to insure that no plastic is left in the well bore and toincrease the permeability of the consolidated formation, it is desirableto overflush the formation; that is, displace the treating resin formingliquid into the formation with oil. However, when oil is displaced intothe formation, the eflectiveness of the consolidation treatment isreduced and the critical area directly adjacent to the well bore remainsunconsolidated because some components of the resin-forming mixture aresoluble in oil. A high degree of consolidation around the well bore isadvantageous in order to prevent the well from producing sand.

The improvement of the present invention resides in incorporating withthe oil used to displace the resin-forming mixture a low molecularweight hydroxy aryl compound. Addition of this compound to the oilprevents extraction of the oil-soluble compounds from the resin mixtureand allows the formation immediately adjacent the well bore toconsolidate. Additionally, it permits the total volume of the formationtreated to have a greater strength than otherwise could be obtained. Thedisplacing oil may include crude oil, diesel oil or any other petroleumfraction. Preferably, the hydroxy aryl compound to be used with thedisplacing oil includes cresol, phenol, or cresylic acid. The amount ofthe hydroxy aryl compound to be employed is approximately 5% by volumeof the oil. The optimum amount to be used in any particular applicationmay be determined, for, as appreciated by those familiar with this art,the technique involves establishing equilibrium between theconcentration and solubility of the hydroxy aryl compound in the twosolvents, i.e., the aldehyde of the resin-forming liquids and the dieseloil of the overflush liquids. The equilibrium is dependent upon thepartition coefficient. The principles of the equilibrium by applicationof the partition coefficient as well as the dependence of the partitioncoefficient on temperature is discussed in The Principles of ChemicalEquilibrium by Kenneth Denbigh, Cambridge University Press, 1955, pages254 and 255 under 8.7 Nernsts Law. Thus, the best concentration of thehydroxy aryl compound in the overflush to fit a particular fieldcondition is ascertainable by experiments in which incremental additionsof the hydroxy aryl compound to the overflush oil and extraction of theresin solution with the oil are made until a concentration is found inwhich there is no exchange of the hydroxy aryl compound between the twodifferent solutions.

Thus, an object of this invention is to provide an improved method forconsolidation of sands in wells through injection of sand consolidationfluids into the formations.

For a more complete understanding of the invention, reference is nowmade to the drawing wherein:

FIG. 1 is a cross-sectional view of a borehole penetrating a subsurfaceformation illustrating the results of displacing into the formation aresin solution with oil containing no hydroxy aryl compound; and

FIG. 2 is a cross-sectional view of a borehole pene trating a subsurfaceformation illustrating the results of displacing into the formation aresin solution with oil containing hydroxy aryl compound.

Referring to the drawing in greater detail, in FIGS. 1 and 2 is shown aborehole 10 penetrating an unconsolidated formation 11. A casing 12perforated adjacent formation 11 and cemented in place by means ofcement 13 is arranged in borehole 10. The perforations designated 14extend through casing 12 and cement 13 into formation 11, as shown.

Referring specifically to FIG. 1, when a resin solution is displacedinto formation 11 through perforations 14 with an oil containing nohydroxy aryl compound, the areas designated 15 remain unconsolidatedafter a resin solution treatment of a zone 16. Therefore, the volume ofsand designated 15 will be produced when production is started.

Referring specifically to FIG. 2, when a resin solution is displacedinto formation 11 with an oil containing hydroxyl aryl compound, nounconsolidated areas 15 remain after treatment. All the sand contactedwith the resin solution is consolidated and the well will produce nosand when production is started. Additionally,

the strength of treated zone 16 is greater when an oil,

containing hydroxy aryl compound is employed.

The practice of the invention is illustrated by the followingexperimental procedures:

PROCEDURE I Treatment employing acidic catalyst Sand was packed in a 1%inch diameter glass column equipped with heads and suitable connectionsto permit fluids to flow through the column and saturated with 10%sodium chloride solution. Then, the sand was flushed with diesel fuel toa low water saturation and the glass column was placed in a 130 F. waterbath. Thereafter, the sand was flushed with an aqueous solution whichconsisted of one part stannous chloride and 10 parts water (2 porevolumes). A plastic solution composed of 2 parts formalin, 1 partphenol-cresol and 6% by weight stannous chloride then was injected intothe sand column after which the sand was flushedwith either diesel fuelor diesel fuel containing by volume cresol or crude oil containing 5%cresol (2 pore volumes). The plastic injection and the oil flushingsteps were repeated after a lapse of 3 hours. The column remained in thewater bath 24 hours after which it was removed for testing.

PROCEDURE II Treatment employing alkaline catalyst The initial steps ofprocedure II, up to and including placing the glass column in the 130 F.water bath, were the same as those of procedure I. Following these stepsthe sand was flushed with methanol (2 pore volumes). A plastic solutioncomposed of 4 parts formalin, 1 part cresol, guanidine carbonate and 3%sodium hydroxide (4 pore volumes) then was injected into the sand.Thereafter, either diesel fuel or diesel fuel containing 5% by volumecresol (2 pore volumes) was injected into the sand and after remaining24 hours in the water bath the column was removed therefrom for testing.

The technique of flushing with methanol prior to injection of the resinforming solution is embodied in copending patent application Ser. No.759,442, entitled Method for Consolidation of Sand, by R. E. Williamsand H. H. Spain, filed September 8, 1958.

The sodium hydroxide was employed as a co-catalyst in order toaccelerate the rate at which the resin solidifies.

The data obtained from these experiments are shown in the followingtable:

an increase from 40 to 480 p.s.i. As to permeability, run No. 2 shows anincrease from 692 md. to 717 md. Further, in runs 2 and 3, maximumstrength at the inflow end of the tube was shown, whereas in run N0. 1,the inflow end of the tube was unconsolidated.

Field runs which illustrate the practice of the invention are shown inthe following table:

TABLE II.-FIELD RESULTS The field results also reflect the improvedresults. When employing cresol in the displacing oil, no sand wasproduced whereas when employing only the oil some sand was produced whenproduction started. The field results were predictable from thelaboratory results.

Having fully described the objects, method, and apparatus of theinvention, we claim:

1. A method for consolidating the sands of an incompetent subsurfaceoil-bearing formation comprising introducing into said formation amixture of resin-forming liquids comprising a low molecular weighthydroxy aryl compound, a water-soluble aldehyde, and a catalyst, whichliquids react and set in said formation and bind the sand particlesthereof together; and then overflushing the formation by introducing oilcontaining a low molecular weight hydroxy aryl compound into theformation following introduction into the formation of the resin-formingliquids and prior to the reaction and setting of the resin-formingliquids, the hydroxy aryl compound in the oil being in an amountsufiicient to prevent extraction of the hydroxy aryl compound from theresin-forming mixture by the overfiush oi-l.

TABLE L-LABORATORY RESULTS Results of consolidation Bun Consolidationtreatment Composition of oil used to Remarks No. displace the resinsolution Mar. com- Permeprcsslve ability, stren th md.

1.--- A field sand treated with 2 stages of phenol- Diesel fuel 89 692Inflow end of tube was unconsolicresol lormaldehyde plastic solution,SnCh dated. catalyst, at 130 F. temperature. 2 do Diesel fuel containing5% 8 M1. 716 717 Maximum strength at inflow end cresol by volume. oftube. 8 do Crude oil containing 6% 3 M.P. 1,020 in Do.

cresol by volume. 4--.. Field sand treated with methyl alcohol, 1 stageDiesel incl 40 m cresol-iormalln plastic solution, NaOH-GunnidineCarbonate Catalyst. 5 do Diesel fuel containing 5% cresol by 480 8, 200

volume.

1 Not measured.

1 Norn.-p.s.t.pounds per square inch; md.-millldarciea.

The addition of a low molecular weight hydroxy aryl compound to theoverfiush oil in runs 2, 3, and 5, show the advantageous results forcompressive strength and permeability. As to compressive strength, runNo. 2 shows an increase from 89 to717 p.s.i.; run No. 3 shows 2. Amethod as recited in claim 1 including employing an acidic catalyst assaid catalyst.

3. A method as recited in claim 1 including employing an alkalinecatalyst as said catalyst.

4. A method as recited in claim 1 including employing an increase from89 to 1020 p.s.i.; and run No. 5 shows cresol as the hydroxy arylcompound in the oil overflush.

5. A method as recited in claim 1 including employing 8. A method asrecited in claim 7 including employing phenol-cresol as the lowmolecular weight hydroxy aryl sodium hydroxide in the catalyst.compound, formaldehyde as the aldehyde, and stannous chloride as thecatalyst. References Cited in the file of this patent 6. A method asrecited in claim 1 including employing 5 UNITED STATES PATENTS cresol asthe hydroxy aryl compound in the resin-forming mixture. 2,378,817Wrightsman et'al June 19, 1945 7. A method as recited in claim 1including employing 2,457,160 Kurtz et a1. Dec. 28, 1948 cresol as thehydroxy aryl compound, formaldehyde as 2,476,015 Wrightsman July 12,1949 the water-soluble aldehyde, and guanidine carbonate as 10 2,513,614Barkhuff July 4, 1950 the catalyst in the resin-forming mixture.2,714,929 Nowak Aug. 9, 1955

1. A METHOD FOR CONSOLIDATING THE SANDS OF AN INCOMPETENT SUBSURFACEOIL-BEARING FROMATION COMPRISING INTRODUCING INTO SAID FORMATION AMIXTURE OF RESIN-FORMING LIQUIDS COMPRISING A LOW MOLECULAR WEIGHTHYDROXY